Known techniques relating to electroconductive tin oxide particles include those described in patent Literatures 1 and 2 below. Patent Literature 1 discloses fine particles of oxygen-deficient tin oxide having an oxygen to tin atomic ratio, O/Sn, of 1.75 to 1.95. The tin oxide particles are described as being free from antimony that imparts an undesirable black color to tin oxide and yet equal to antimony-containing tin oxide in electroconductivity. The tin oxide particles are obtained by mixing a tin compound solution with an acid or alkali aqueous solution, adding a phosphorus compound to the resultant reaction mixture to form a precipitate, washing, drying, and grinding the precipitate, and firing the resulting particles in the atmosphere.
Patent Literature 2 discloses white electroconductive powder composed of a particle of a complex oxide comprising Al2O3, TiO2, and SiO2 and an antimony-doped tin oxide layer on the surface of the particle. Patent Literature 2 describes the electroconductive powder as being excellent in electroconductivity and whiteness. The electroconductive powder is obtained by dispersing the complex oxide particles in water, adding dropwise to the resulting aqueous dispersion a mixed aqueous solution containing a tin source and an antimony source along with an alkali aqueous solution to precipitate an antimony-doped tin oxide compound on the surface of the complex oxide particles, and firing the particles in the atmosphere.